Mercruiser 3.0 Delco EST wont start

[fat fanny]

Re: Mercruiser 3.0 Delco EST wont start

If the above test Don suggested passes I would most definately take the ingnition module out and take and have it cycle tested they do have histories of intermittently working and not! Then move onto the entire wiring harness remove and perform a continuity test on every single lead (especially the 12v feed purple) and all swithes ignition, lanyard and breaker. Good luck!!!!

 

[Maxum2006]

Re: Mercruiser 3.0 Delco EST wont start

I asked this before, will ask again. Do you have voltage to the purple wire on the coil WHILE the engine is cranking over with the starter. That is what you must answer at this point.


EDIT you posted while I was typing.

Don, I will try this when I am home this weekend and post back. I only get to visit the boat on weekends as we are busy in work.

When I do the test I will post the answer. Could you tell me what to look for next if...

a) there remains a steady 12-13v when cranking
b) there is a cycle of voltage, i.e off on off on
c) there is no voltage

This way I will be able to make some progress and not just one thing on the weekend. An electrician in work recommended
me to use an analogue meter as digital volt meters can sometimes be too sensitive and give you a false interpretation if the voltage fluctuates rapidly, or even perhaps use a small 12v bulb. What do you think?

Thanks

 

[Don S]

Re: Mercruiser 3.0 Delco EST wont start

Perhaps this will help.

 

[Maxum2006]

Don - you replied to a comment regarding my 3.0L Mercruiser, Delco EST spark problem post - only now I am getting around to look at this!!! Because I only get to see the boat infrequently - I have just ordered from re-power marine in Falmoth - a new distributor, new coil, new rotar arm, new plug leads, new HT lead and new spark plugs!! http://www.ebay.co.uk/itm/Ignition-...ltDomain_3&hash=item3ccf9e79e4#ht_1986wt_1174



I have a funny feeling that this may not even be the case - but I would rather not waste time - and I will always have them as spares should they ever need replacing!



You asked me to do a test which was ' test the voltage to the purple wire when the engine is cranking', I will look at this test this weekend, I know that I do get 13V when the ignition is on, but not checked it with an analogue meter - will do this the weekend.



Can you give me the next steps if;



a) 13V constant when cranking

b) 13V on and off when cranking

c) 0V when cranking



You mention that it could be the 'starter switch' - what and where is this? Is it my ignition key switch on the dashboard?



Thanks



Dave

 

[achris]

Hi Dave,

Don passed away in July 2013...

I'm just about to head off to bed, I'll look at your question in the morning...

Chris......

 

[Maxum2006]

Chris,

Thanks for the reply.

That is very sad indeed. He seemed a very knowledgable chap. My regards go out to his family and friends.

I am sure if he was around he would be replying with various other tests for me to conduct.

I have done the following;

Fitted a new distributor cap - still no spark
Fitted a new rotor arm - still no spark
Read 13.5v on the purple wire to the coil when ignition on
Read 10v on the purple wire to the coil when engine cranking

Things to try next -

1) Renew the plug leads and HT Lead
2) Fit the new coil properly (I could not bolt it to the engine frame correctly - I had to crank it with it hanging off a cable tie as my torques socket was too big to fit on bolts for coil (I wonder if the coil needs to make contact with the engine block to act as a ground - I really doubt this as the spark is needed to travel through HT lead)
3) Replace x4 spark plugs (don't think will help as old ones have only done about 5 hours).

Worth noting - when I was cranking the engine with the ignition key - the key barel itself snapped off (thin cheap plastic) the ignition on the back had the lugs SBI I am guessing S for the solenoid (starter motor) , B for the battery and I for the ignition (I.e. The 12v to my coil). It looks very flimsy plastic.

Also note that when trying out the other gauges, x3 out of the 6 toggle switched with limitation (I.e. Blower, accessory, navigation lights etc) all snapped off in my hand. What on earth is going on with this boat. The components are really poor quality - they have probable only ever been switched on and off about 50 times. Why on earth is it falling apart. It's only 9 years old!!! They are made by Carling Technologies.

Anyway - I would glady hear others thoughts as to what to try next .... This is really beginning to get me down.

Thanks

Dave

 

[achris]

12v on the coil is good. Check that you also have 12v on both sides of the shift interrupt switch. One wire is purple, the other white/green.

 

[Maxum2006]

12v on the coil is good. Check that you also have 12v on both sides of the shift interrupt switch. One wire is purple, the other white/green.

Chris - with regards to the shift interrupt switch - I have a rough understanding that basically this switch is positioned next to the throttle arms which are mounted on a bracket on the top of the engine. Basic function of this switch is to temp kill or suppress the spark to enable the selection of forward or reverse.

When I am trying to crank - the throttle handle (I.e. The arms you use to put up or down for forward and reverse) is in the upright locked position - I.e. Neutral. In this position, the shift interrupt switch is 'not made' i.e. The little button on the end is not pressed in. I have disconnected the shift interrupt switch and tested for continuity at this position (in neutral) and the circuit is open. I then used a small flat screwdriver to make the switch (i.e. Push the button in) and then the circuit is made - and I have continuity.

So to recap - when in neutral shifter position and trying to start - the shift interrupt switch is open, and when the button pressed in with my screwdriver (normally actuated by an armature on the throttle cable) the circuit is made.

Another way to test for this is to just disconnect the shift interrupt switch and leave the two wires separated - this eliminates the switch.

I have done this an still no spark.

Have I got this right? Should the switch be normally open circuit and when the switch is made then the circuit is made - or should it be the other way around - i.e. Always made and when the button pressed it breaks the circuit? If so then an easy way to rectify this is to just disconnect the shift interrupt switch and join the two cables together. I know isn't a long term solution - but at least I will be able to get a spark and be confident that this is the reason for non spark and order a new switch?

Any other thoughts?

 

[Fun Times]

Hi there, just to clarify, the shift interrupt switch Chris mentioned is located at the shift bracket assembly mounted on the engine and will look like this as a whole and item 18 is the switch in question. http://www.mercruiserparts.com/Show...9.png&inbr=11669&bnbr=200&bdesc=Shift+Bracket

Since you have no spark, try this. Connect your standard test light to battery positive and touch the negative (-) side of the coil post and have someone crank the engine over.....The test light should blink. If it don't then you should/may have a bad ignition module or pickup coil found under the distributor cap. Item numbers 4 & 6. http://www.mercruiserparts.com/Show...=50&bdesc=Distributor+and+Ignition+Components

If it blinks but no spark = bad ignition coil. Test 6 & 7 are A good understanding of the system.
http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/distributor-mounted-icm-tests-5

Also AC Delco part number D1965A ignition control module is the much more affordable way test/try a new module as it's the equivalent as the Mercruiser module.

 

[achris]

Ok, doesn't sound like it's a shift interrupt switch problem. (sometimes they fail and cause a 'no spark' condition). The other thing that should also be checked is the tacho. Disconnect the gray wire on the back and then check for spark.

Chris......